This invention relates to aluminum wheel covers, and more particularly, to an aluminum wheel cover wherein a phantom draw bead is utilized during the manufacturing operation.
Wheel covers are well known to the art and are generally drawn from a blank of relatively thin sheet metal into a generally circular configuration having a given ornamental profile or given design contours. These wheel covers have been formed from cold work hardened material such as brass and, more prevalently, stainless steel. The cover is fastened to the automotive wheel by means of resilient teeth which are either provided integral with the cover member or by way of a retention bank which, in turn, is suitably fastened to the cover member such as by rolling or clinching an outer edge of the cover member about the retention band. More recently, wheel covers have been provided as a two piece aluminum wheel cover wherein the cover member is provided of aluminum which is attached to a stainless steel retention band. Such aluminum wheel covers are disclosed in the copending application of L. Kafoure and D. J. Toal, Ser. No. 551,095, filed Feb. 20, 1975, which is assigned to the same assignee as the present invention.
The prior art stainless steel wheel covers are formed by placing a sheet metal blank between the cooperating dies of a press. The dies are then advanced toward one another until an outer annular portion of the upper die engages and clamps a corresponding outer annular margin of the blank while forming a draw bead thereat. The draw bead is utilized to secure the blank from undesired movement during the subsequent forming operation wherein the sheet metal blank is essentially pulled over the lower die to provide the desired profile or contours. Thereafter, the draw bead is trimmed off as waste or scrap material and the remaining drawn blank is subjected to subsequent restrike and forming steps to provide the desired finished product. In the U.S. Pat. No. 3,001,494, to Lyon there is disclosed a method and apparatus wherein a portion of an external draw bead is deliberately drawn in a direction toward the center of the blank during the forming operation thereby to minimize the scrap material. It can be seen by reference to this patent, however, that substantial scrap nevertheless results. Further, the portion of the draw bead which is drawn radially inwardly is disposed along the outer annular radially facing flange which is subsequently turned over and which therefore is not visible from the external surface of the finished product.
Aluminum wheel covers have been provided in limited duty applications such as recreational vehicles or campers. These covers have utilized a relatively thick, soft and generally unfinished (i.e., not annodized or otherwise surface treated) cover member which is fabricated to attain the desired shape and contours. This has the disadvantage that the thickness results in a relatively heavy and expensive cover; which is not particularly durable due to the soft characteristics of the aluminum; and, when the aluminum is unfinished it is generally unacceptable in terms of meeting the decorative requirements of the industry which is accustomed to polished stainless steel wheel cover surfaces.
These and other disadvantages are overcome by the present invention wherein apparatus and method are provided for making generally circular aluminum wheel cover members in a drawing process wherein minimum blank sizes are accommodated and wherein the aluminum material can possess the desired hardness and treated surface properties. This is accomplished by utilizing a phantom draw bead in accordance with the principles of the present invention.